自适应卡尔曼滤波在航空发动机参数估计中的应用

介绍根据实际飞行数据并用卡尔曼滤波方法对某型发动机的参数估计及其结果。重点研究了卡尔曼滤波在航空发动机参数估计中的滤波发散问题和解决这一问题的自适应卡尔曼滤波、飞行条件补偿及模型修正的综合方法。      

非线性分离算法及其在飞行试验中的应用

 本文根据最小方差估计和分离算法原理,提出一种新的非线性状态估计和偏差辨识的分离算法。并用此算法确定飞行状态和测试仪器的误差,同时U-D分解保证计算效率和数值稳定性。为了得到数据相容性检验的准确结果,本文采用直接离散化的飞机运动模型,以减小模型误差。通过仿真并在我国两种歼击机上实际应用,结果表明本文所给的算法对不同的初值和噪声统计特性都能得到飞行数据相容性检验的一致结果,并能用于低采样率下的数据相容性检验。     

无人机动态RCS测量及数据统计分析

以某无人机的动态RCS特性作为研究对象,设计了无人机的测试飞行航路,应用非线性最小二乘估计方法,对采集到的无人机动态RCS试验数据进行X^2分布和对数正态分布模型的参数估计,降低了测量噪声对统计模型参数估计的影响,较为理想地解决了数学统计模型参数估计中试验数据测量噪声的影响,并对某无人机的动态RCS统计分布特点做了分析。     

利用飞行试验数据对发动机参数估计的研究

本文研究利用不同飞行状态下测量的发动机变量估计涡轮进口温度和压气机出口压力。参数估计法采用多元线性回归分析法。根据变量选择的综合最优原则 ,从 6个测量变量中选择了回归方程的自变量 ,建立仅包含 3个发动机测量变量的回归模型 ,参数估计结果证明模型的估计精度是满意的。本文还介绍了利用专用设备在线录取发动机变量的数据处理方法。     

A practical filter error method for aerodynamic parameter estimation of aircraft in turbulence

It is common for aircraft to encounter atmospheric turbulence in flight tests. Turbulence is usually modeled as stochastic process noise in the flight dynamics equations. In this paper, parameter estimation of nonlinear dynamic system with both process and measurement noise was studied, and a practical filter error method was proposed. The linearized Kalman filter of first-order approximation was used for state estimation, in which the filter gain, along with the system parameters and the initial states, constituted the parameter vector to be estimated. The unknown parameters and measurement noise covariance were estimated alternately by a relaxation iteration method, and the sensitivities of observations to unknown parameters were calculated by finite difference approximation. Some practical aspects of the method application were discussed. The proposed filter error method was validated by the flight simulation data of a research aircraft. Then, the method was applied to the flight tests of a subscale aircraft, and the aerodynamic stability and control derivatives were estimated. All the estimation results were compared with the results of the output error method to demonstrate the effectiveness of the approach. It is shown that the filter error method is superior to the output error method for flight tests in atmospheric turbulence.     

导弹飞行数据的相容性检验研究

本文针对导弹飞行试验的特点,采用导弹六自由度动力学方程建立了飞行数据相容性检验的数学模型。在有舵偏激励同时考虑偏差间相关性的条件下,应用广义Kalman滤波方法进行常值及比例因子偏差的估计。仿真及实际应用表明所建数学模型及估计方法正确有效,所得结果与由高速可重复模拟匹配技术结果极为接近。     

基于遥测数据的无人机气动参数辨识方法研究

针对无人机在高空低速飞行时易受风场影响及在数据分析时遥测数据不完备的问题,进行了气动参数辨识方法研究,提出了基于空速管平面矢量三角形的风场估计方法及基于风场信息修正的气动角估计方法。以某型无人机为例,对遥测数据进行了充分分析与信息综合,运用逐步回归方法进行了纵向气动参数辨识,并进行了实验验证。结果表明,模型计算结果与实测数据吻合较好,说明所提方法有效。考虑到辨识模型的数学本质,该方法对其他固定翼无人机同样适用。     

一种飞行器投放分离气动力辨识修正方法

空中投放发射的大翼面飞行器的分离轨迹与姿态受载机干扰流场影响更加明显,对分离时干扰气动数据库的准确性提出了更高要求。针对投放分离干扰气动力特点,提出了一种简化的差量气动力模型,并给出了一套飞行数据处理与参数预估计的方法。分离段飞行数据的辨识结果与六自由度飞行动力学仿真结果说明了提出的差量气动模型与相关数据处理方法的有效性。用辨识结果对气动数据库进行修正提高了数据库的准确度,可提高分离安全飞行仿真分析的精度。     

飞行数据相容性检验的极大似然方法

 本文提出了一种有效的飞行仪器偏差估计的极大似然方法。为了提高对偏差估计的精度,采用了最小二乘方法对角速率,过载的测量量进行平滑,以减小系统噪声对估计精度的影响;并给出了灵敏度矩阵和初值的确定方法以保证算法的收敛速度。通过数字仿真和对我国几种不同类型飞机的飞机数据实际计算表明,提出的方法能够较准确地辨识出测量仪器的偏差,比普通极大似然法更有效。     

利用飞行试验信号对发动机模型辨识的研究

 利用飞行试验信号对发动机模型辨识进行了研究。在飞行过程中,发动机将受到各种随机扰动的作用,这种扰动将引起发动机特性的变化、在这种情况下,利用与发动机特性有关的信号进行发动机数学模型辨识对发动机自适应控制和状态监控有实际的意义。飞行试验是在H=3km、v=770km/h和H=13km、v=1540km/h时进行的,利用机载信号采集与记录设备录取了试验信号。介绍了信号的平滑和滤波方法,讨论了巴特沃思滤波器的设计和参数选择。为了得到无偏估计,采用递推广义最小二乘方法进行辨识,并得到了辨识结果。     

A comprehensive survey on the methods of angle of attack measurement and estimation in UAVs

Angle of Attack (AOA) is a crucial parameter which directly affects the aerodynamic forces of an aircraft. The measurement of AOA is required to ensure a safe flight within its designed flight envelop. This paper intends to summarise a comprehensive survey on the measurement techniques and estimation methods for AOA, specifically in Unmanned Aerial Vehicle (UAV) applications. In the case of UAVs, weight constraint plays a major role as far as sensor suites are concerned. This results in selecting a suitable estimation method to extract AOA using the available data from the autopilot. The most feasible and widely employed AOA measurement technique is by using the Multi-Hole Probes (MHPs). The MHP measures the AOA regarding the pressure variations between the ports. Due to the importance of MHP in AOA measurement, the calibration methods for the MHP are also included in this paper. This paper discusses the AOA measurement using virtual AOA sensors, their importance and the operation.     

军用飞机状态估计与参数辨识软件包研制

在对最优输入设计、数据协调和数据分析分别进行研究的基础上,应用软件工程化方法研制出相应的软件,再通过管理软件进行统~管理,集成了~个完整的军用飞机状态估计与参数辨识软件包MASEPI。最后,通过仿真测试和实测数据处理,该软件包的有效性和实用性得到了验证和确认。现已应用于实际工程试验与试飞数据处理。     

Flight path estimation using frequency measurements from a wideaperture acoustic array

A narrowband technique based on the acoustical Doppler effect is proposed for estimating the trajectory of a turbo-prop aircraft in level flight with constant velocity as it transits over a ground-based passive acoustic sensor array. The basic principle is to measure the temporal variation of the instantaneous frequency (IF) of the acoustic signal received by each sensor and then to minimize the sum of the squared deviations of the IF estimates from their predicted values over a sufficiently long period of time for all sensors. The technique provides estimates of the propeller blade rate and the five source motion parameters that describe the aircraft trajectory. The six dimensional minimization problem is reduced to a five dimensional maximization problem, which is solved numerically using the quasi-Newton method. A simple method is described that provides the initial parameter estimates required for the numerical maximization. The effectiveness of the motion parameter estimation technique is verified using real acoustic data recorded from a wide aperture microphone array during various transits of a turbo-prop aircraft     

Non-linear aircraft flight path reconstruction review and new advances

Aircraft parameter identification techniques have become accepted as indispensable tools in the evaluation of prototype- and derivative aircraft in flight. Applications include estimation of stability- and control derivatives in the linearized equations of motion, synthesis of nonlinear aerodynamic and propulsion models in the context of performance certification and incorporation of information from dynamic flight test manoeuvres in a priori nonlinear flight simulation models. A variety of techniques in the time- as well as the frequency domain have been applied in the past. One of the successful techniques is the so-called two-step method (TSM) in which the original state-parameter estimation problem is decomposed into a nonlinear state/parameter estimation or reconstruction problem and a subsequent linear parameter identification problem. In the literature, the first step of the TSM is often referred to as `flight path reconstruction'. The present paper focuses on the first step of the TSM. After a derivation of the system models describing the flight path relative to a flat earth as well as a spherical and rotating earth, and observation models for air data and GPS, the flight path reconstruction problem is introduced. Requirements with respect to type and quality of flight test transducers are discussed. Next follows an overview of different approaches to the solution of the flight path reconstruction problem with emphasis on Kalman filter/smoother and Maximum Likelihood methods. A new adaptive algorithm is presented, the Modified Recursive Maximum Likelihood Adaptive Filter (MRML) which is shown to be significantly more robust with respect to initialisation errors than earlier methods. A reconstructibility analysis is presented for different transducer combinations. Numerical examples are presented based on simulated as well as actual flight test data. Flight results are given of the flight path reconstruction part of an on-line pseudo real-time application of the TSM. The paper ends with concluding remarks.     

极大似然法及在有控飞行器气动参数辨识中的应用

 <正> 一、引言 飞行器气动参数辨识作为系统辨识理论在航空、宇航领域的应用分支,在一些发达国 家受到了相当的重视,并且从70年代以来已形成了气动参数辨识软件包,不仅缩短了飞行器的设计、改型及性能分析的周期,并且还具有靠风洞实验或理论分析所不具备的优点。目前飞行器的气动参数辨识虽已有很大发展,但是对有控飞行器的闭环辨识问题仍未解决,分析传感器非线性因素对气动参数辨识结果的影响也不够深入。本文使用极大似然法,结合某有控飞行器的全弹道仿真数据,研究了在闭环飞行状态下进行气动参数辨识所存在的问题,分析了传感器的非线性因素对气动参数辨识的影响。     

Aerodynamic Modeling and Parameter Estimation from QAR Data of an Airplane Approaching a High-altitude Airport

Aerodynamic modeling and parameter estimation from quick accesses recorder (QAR) data is an important technical way to analyze the effects of highland weather conditions upon aerodynamic characteristics of airplane. It is also an essential content of flight accident analysis. The related techniques are developed in the present paper, including the geometric method for angle of attack and sideslip angle estimation, the extended Kalman filter associated with modified Bryson-Frazier smoother (EKF-MBF) method for aerodynamic coefficient identification, the radial basis function (RBF) neural network method for aerodynamic modeling, and the Delta method for stability/control derivative estimation. As an application example, the QAR data of a civil airplane approaching a high-altitude airport are processed and the aerodynamic coefficient and derivative estimates are obtained. The estimation results are reasonable, which shows that the developed techniques are feasible. The causes for the distribution of aerodynamic derivative estimates are analyzed. Accordingly, several measures to improve estimation accuracy are put forward.     

一种基于短时机动试飞数据的动力学辨识优化方法

飞行动力学辨识算法的一个关键问题是,如何通过简单的机动获取所关心频率范围的响应特性。短时倍脉冲是一种易于实施的激励信号,兼顾试飞安全性与经济性,但与频域辨识法通常使用的扫频输入激励相比,短时机动频谱范围窄、信噪比低,一般难以得到准确的辨识结果。对如何基于短时机动飞行试验数据,提高辨识结果准确性的问题进行了研究。首先分析了经典Welch谱估计进行时域-频域转换过程中,影响非参数模型辨识精度的主要因素,提出了削减窗函数边缘缩减效应的数据预处理方法,并结合多窗口综合技术,提高频域特性辨识结果的精度。在参数化模型辨识过程中,针对有限频谱范围,提出了利用相干函数和功率谱密度加权综合,确定等效拟配的频率范围和频率节点的自适应方法,使得低阶等效拟配与输入激励信号高度相关,提高参数化模型辨识的精度、一致性和适应性。通过不同类型飞机的大量短时机动和少量扫频飞行试验数据模型辨识的工程应用示例,验证了动力学辨识优化方法算法稳定、结果准确,可满足飞行品质模态特性评价等应用需求。     

涡轴发动机自适应混合诊断模型高斯加权聚类方法

针对整个飞行包线内涡轴发动机健康参数估计问题,提出基于高斯加权聚类的机载自适应混合模型建立方法.机载自适应混合模型由卡尔曼滤波器和神经网络组成,由于飞行数据样本庞大,采用高斯加权模型对涡轴发动机飞行数据进行实时聚类,利用聚类数据更新神经网络权重,并实现自适应混合模型工作范围的自动扩展.仿真结果表明了该方法的有效性,采用...     

歼击机结构故障的模式识别与参数辨识新方法

针对自修复飞行控制系统的故障,采用基于精确线性化的方法,在原空间和特征空间提出了基于双假设/多假设（增强型）概率统计学的模式识别与参数辨识方法,给出了结构故障的可识别性和可辨识性的判别准则,并以某型歼击机为例进行了仿真研究。     

推力矢量飞机自适应控制系统仿真平台研究

研究了具有自修复功能的推力矢量飞机自适应控制系统的结构功能特点,研究了RHO优化控制算法实现在线控制器设计,利用MSLS辨识算法实现在线飞行参数辨识和等价空间算法、传感器信息融合技术和概率统计理论实现FDI算法。并且根据系统各个部分的算法,采用面向对象技术语言VC 6.0和三维图形语言OpenGL开发了仿真平台,利用仿真平台实时演示了飞机存在舵面故障情况下的飞行控制系统运行仿真,解决了飞机飞行过程中存在舵面损伤和气动参数变化的问题,该仿真平台可以根据需求进行飞机故障加载,具备完备的推力矢量飞机自适应控制系统仿真功能。